Toughening mechanism of medium carbon pearlitic steels for high speed wheel
ZHOU Shi-tong1， 2， LI Zhao-dong2， PAN Tao2， ZUO Yue3， YANG Cai-fu2， YONG Qi-long2
（1. Department of Materials Science and Engineering， Kunming University of Science and Technology， Kunming 650093， Yunnan， China； 2. Institute of Structural Steels， Central Iron and Steel Research Institute， Beijing 100081，China； 3. Institute of Welding， Central Iron and Steel Research Institute， Beijing 100081， China）
Abstract：Toughness is the key performance index affecting the safety of high speed wheel. In order to clarify the toughening mechanism of medium carbon pearlitic steel for high speed wheel，toughening through inclusion modification and microstructural control was intensively investigated. It was found that the toughness of wheel steel was improved by formation of oxide-sulfide duplex inclusion （sulfide-encapsulated oxide）. The oxide inclusions easily induced crack initiation at the inclusion/matrix interface and the crack could propagate into the surrounding matrix，while the crack initiation of duplex inclusions was only on the inclusion itself so that the crack propagation to the matrix was hindered. When the mass percent of sulfur was increased to more than 0.006% （for a given manganese mass percent of 0.75%），the oxide inclusions could be well encapsulated due to the precipitation of sulfides beyond the solidus temperature. During hot working of wheel steel，the sulfides could be dissolved and re-precipitated in austenite，leading to a change for the duplex inclusions. However，the thermal stability of duplex inclusions could be improved by increasing the mass percent of sulfur or decreasing the hot working temperature. The austenite grain size and ferrite volume fraction were the key reasons for the toughening of wheel steel microstructure. The cleavage facet size was decreased and the ductile tearing area was increased with refinement of austenite grain size and enhancement of ferrite volume fraction.
周世同， 李昭东， 潘 涛， 左 越， 杨才福， 雍岐龙. 中碳珠光体型高速车轮钢的韧化机理[J]. 钢铁, 2019, 54(2): 75-82.
ZHOU Shi-tong1， LI Zhao-dong2， PAN Tao2， ZUO Yue3， YANG Cai-fu2， YONG Qi-long2. Toughening mechanism of medium carbon pearlitic steels for high speed wheel. Iron and Steel, 2019, 54(2): 75-82.
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2019, Vol. 54 
